Control System Design and Experimental Verification of a Self-Bearing Double-Stator Linear-Rotary Actuator

Integrated Linear Rotary Actuators (LiRAs) offer a compact solution which can achieve high dynamics when coupled linear and rotary motions are required. As a further step in integration, the LiRA can be equipped with Active Magnetic Bearings, which however requires a special winding configuration and feedback control of the magnetically levitated mover's position to operate. In this paper a control-oriented analysis of a Self-Bearing (SB) Double-Stator (DS) LiRA is conducted, providing an insight on simultaneous bearing force and torque generation and deriving an electromechanical dynamic model which is linearized and used to design a 6-DoF cascaded position control system. This is then implemented in hardware and verified, bringing a prototype of the SB DS LiRA into full operation, tracking a linear-rotary mission profile with radial deviations of the levitated mover's position below 75 μm.